The proposed work concerns investigations on mammalian genetics and development. The technical approach makes use of somatic cell genetics analysis. Genetic investigations will center on developing new approaches to parasexuality in mammals, such as gene transfer and somatic recombination. Panels of hybrid cells will also be developed for use in gene mapping. Developmental studies will emphasize investigation of the modulation of differentiated traits in hepatocytes, erythrocytes, and plasmacytomas. Investigations on the regulation of interferon will continue. Genetic and developmental studies will also be directed toward an understanding of the structure and function of various membrane receptor sites.